These things do happen. A number of years ago I worked as an Insurance Broker placing Marine business for our German Clients as part of the European Division.
When Christmas came around, the company supplied the Christmas cards to be sent to our clients and for one reason or another I was away when the majority of the cards were given out. When I was back in the office I was given my cards, one of which was a nice shot of a large fishing vessel going out to sea with snow falling. A nice attractive seasonal marine scene you may think.
When I looked inside the card, it stated that the Fishing Vessel whatever, going to sea in the winter of 1920. It then went on to say, that in WW1 this vessel sank two German U Boats while acting as a Q ship.
I mentioned this to my Director and as you can imagine panic hit the post room with every card going to Europe being checked, however the horse had in most cases bolted. Hundreds of these Christmas cards were sent to our European clients.
Our German and Austrian clients had a major sense of humour failure, whilst the French, Belgian and others thought it was brilliant, which didn't help the Germans and Austrians.